Living in Missoula, Montana does not provide for quality higher end stores to listen to subwoofers to determine what I want or need for both music and HT listening. So I try to read and understand input from others who know far more than me. Which SubWoofer to buy and why? If we only hear to 20 Hz and feel bass from there, are we wanting the room to shake (more frequency and pressure) to know we have a good subwoofer. Small vis larger box subs to reproduce the lowest bass at high volumes with low distortion. One or two subs to reach down to 18 Hz at -3dB's in the max bass extension mode. SVS (SB12-PLUS), Rel (T2 OR T1), HSU (VTF-3 MK3) have been recommended and all look great, without the ability to listen to them how can I decide which one to choose? Opinions!